The regulation of exhaust gas emissions from automobiles and the like has become more and more strict, and many oxygen sensors have been developed. Under such circumstances, there has been proposed also an oxygen sensor having a layer which includes a catalyst and cerium oxide or the like which have the function of occluding and releasing oxygen (JP Patent Kokai Publication Nos. 61-79155 (1986) and 62-245148 (1986)).
However, oxygen sensors are usually used under conditions of severe heat cycles, and in every oxygen sensor according to the above-described proposal, the layer including cerium oxide and the like and the catalyst peels from the sensor element during its use. Furthermore, cerium oxide and the like and the catalyst are mixedly coated so that, the both components exist in a single layer.